Most county assessor's office have printable GIS maps that show private parcels and public land parcels (for free). This is a good source if you know where you want to hunt in advance. You may need to know a parcel number to get started in the parcel search section, but often an address is good enough. If you have an iPhone or similar, you can probably just work with that same source out in the field (if you have service) without a printed copy. If you're hunting in Wahkiakum Co., don't even bother - I think they're still trying to get electricity there. No digital information whatsoever.
I think X-maps and other similar services provide better maps that show parcels, but cost quite a bit more than the free assessors maps.